Light-emitting diodes (LEDs) are used as the light source for certain motor vehicle headlamps. In certain applications, an LED is affixed to a heat sink, both of which are wholly contained within the confines of the headlamp. In such instance, heat from the LED is transferred to the heat sink, which heats the volume of air within the headlamp. The heat may then be transferred through the lamp housing to an environment outside the housing. However, such heat transfer may not be very efficient, and thus require the use of a relatively large heat sink, which adds weight to the vehicle and increases packaging size. For example, a passive heat sink made of aluminum to transfer heat from a 20 watt LED may weigh up to one pound (453.6 grams), with dimensions of approximately 100 mm×100 mm×80 mm. In addition, the lamp housing must be large enough to allow for air to circulate through the heat sink and to dissipate heat through the housing wall. An example of such a headlamp is the current Ford F-150 headlamp or the Ford Explorer headlamp.
However, while such cooling is sufficient for larger headlamps, which offer a suitable internal air volume and/or housing size for thermal dissipation, such a structure and method for thermal dissipation may be inadequate for smaller headlamps, which may be required to operate at the same power levels as the larger headlamps.
A heat sink may be able to provide more efficient cooling if it extended outside the headlamp housing. However, motor vehicle headlamps, particularly the low and high beam LED modules, generally must be movable (e.g. to tilt/pivot up or down) by a few degrees to allow for adjusting vertical aim. Given the LED module is affixed to the heat sink, the heat sink must also be movable, e.g. to tilt/pivot up or down, to correspondingly move the LED module. However, it has not been possible to tilt/pivot the heat sink, while at the same time extending the heat sink outside the lamp housing to provide more efficient cooling, and sealing the heat sink relative to the lamp housing to inhibit contaminates from entering the lamp housing,